As broadcasting content become digitzed, the protection of the broadcasting contents may become more important. For example, the proliferation of Digital Television may be promoted by the existence of a copy protection device and/or a conditional access device that allows only an authorized user to view the digital broadcast content.
Digital content is encoded at a broadcasting station using a secret key so that the transmitted digital broadcast content may be viewed by only an authorized viewer (i.e., a user that has access to the secret key used to encode the content. The content can be decoded (e.g., in a digital TV) using the secret key, thereby allowing the content to be viewable. It is known to provide some of the above in a “conditional access device” associated with a digital TV.
Further, the digital TV may include a copy protection device to protect against unauthorized copying. In the copy protection device, the content is encoded using the secret key provided in the digital TV when the received digital broadcasting content is stored in a predetermined storage unit, and the stored broadcasting content is decoded using the secret key when the stored broadcasting contents are again viewed (or reproduced).
However, some conventional conditional access devices of the digital TV receive the digital broadcasting contents over a limited channel, decode, and store the content without encoding.